U.S. patent number 6,882,841 [Application Number 09/348,634] was granted by the patent office on 2005-04-19 for method for performing an enhanced random access using information of forward common channels in a mobile communication system.
This patent grant is currently assigned to LG Information and Communications, Ltd., LG Information and Communications, Ltd.. Invention is credited to Young Sik Youn.
United States Patent |
6,882,841 |
Youn |
April 19, 2005 |
Method for performing an enhanced random access using information
of forward common channels in a mobile communication system
Abstract
Method for performing a random access in a mobile communication
system, including the steps of monitoring at base station a state
of a reverse common channel, determining state information of the
reverse common channel corresponding to a result of the monitoring
using one slot allocated to a forward common channel, and
transmitting the state information to respective mobile stations
through the forward common channel, whereby improving a message
transmission efficiency because one random access slot allocated to
the forward common channel is used, not entirely, but partly, or
the state information of the reverse common channel is transmitted
repeatedly for a given times in a case when the base station
transmits state information of the reverse common channel to all
mobile stations within cells of sectors of its own.
Inventors: |
Youn; Young Sik (Seoul,
KR) |
Assignee: |
LG Information and Communications,
Ltd. (Seoul, KR)
|
Family
ID: |
19546436 |
Appl.
No.: |
09/348,634 |
Filed: |
July 6, 1999 |
Foreign Application Priority Data
|
|
|
|
|
Aug 4, 1998 [KR] |
|
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1998-31784 |
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Current U.S.
Class: |
455/434; 370/329;
370/336; 455/515 |
Current CPC
Class: |
H04W
74/006 (20130101); H04W 74/0833 (20130101) |
Current International
Class: |
H04Q
7/20 (20060101); H04Q 007/20 () |
Field of
Search: |
;455/434,515,32.1,435
;370/329,336,311,337,465,470,230 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Gesesse; Tilahun
Attorney, Agent or Firm: Fleshner & Kim, LLP
Claims
What is claimed is:
1. A communication method comprising: monitoring at a base station
a state of a reverse common channel; determining state information
of the reverse common channel corresponding to a result of the
monitoring; broadcasting the state information combined with power
control information based on the state information in a same slot
to a mobile station through a forward common channel using each
slot allocated to the forward common channel; and performing a
random access of slots to transmit data to the base station on the
reverse common channel based on the state information combined with
the power control information.
2. A method as claimed in claim 1, wherein the slot includes at
least two channel information bits and one power or reservation
control bit.
3. A method as claimed in claim 2, wherein, if at least two of the
channel information bits are used the channel information bits are
repeated with an odd number of times.
4. A method as claimed in claim 1, wherein the state information of
the reverse common channel corresponding to the result of the
monitoring determines one of a plurality of preset state
information.
5. A method as claimed in claim 4, wherein the state information
comprises: idle-normal state information representing a state in
which the reverse common channel is in an idle state and not
reserved by a particular mobile station, idle-reservation state
information representing a state in which the reverse common
channel is in a idle state and reserved by a particular mobile
station, busy-down state information representing both a state in
which the reverse common channel is in a busy state and a command
for reducing a transmission power to the mobile station, and
busy-up state information representing both a state in which the
reverse common channel is in a busy state and a command for
boosting a transmission power to the mobile station.
6. A method as claimed in claim 5, wherein the base station
transmits a message for performing a random access in a case when
every even numbered slot with reference to a first slot number of
one frame has the idle-normal state information.
7. A method as claimed in claim 5, wherein the idle-reservation
state information is transmitted in succession loaded on two slots
in a case when the state information transmitted from the base
station to the mobile station is the idle-reservation state
information.
8. A method as claimed in claim 1, wherein the base station
determines the power control command before a starting point of
each slot allocated to the reverse common channel.
9. A method as claimed in claim 1, wherein the base station matches
periods of the reverse slots the mobile station uses to forward
slots before using the reverse slot.
10. A method as claimed in claim 1, wherein the base station feeds
back the state information continuously using a portion of
broadcasting channel.
11. A method as claimed in claim 1, wherein after the transmitting
step, the method further comprises: receiving and analyzing at a
respective mobile station state information of the reverse common
channel; and, performing at the respective mobile station a random
access according to the state information.
12. A method as claimed in claim 11, wherein the message
transmission is stopped if two idle state slots are detected by the
mobile station in succession as a result of monitoring the next
slot after transmission of a message through an arbitrary slot for
performing random access.
13. A method as claimed in claim 11, wherein the mobile station
does not change the transmission power for the idle state
information occurred during performing random access.
14. A method as claimed in claim 11, wherein after the step of
performing a random access, the method further comprises
determining a state of the reverse common channel through
information contained in the next slot.
15. A method as claimed in claim 14, wherein the mobile station
determines as a result of the determination that the random access
is performed properly if the reverse common channel is in a busy
state, and the random access is performed improperly if the reverse
common channel is in an idle state.
16. A method as claimed in claim 15, wherein the mobile station
automatically performs the random access again if it is determined
as a result of the determination that the random access is
performed improperly.
17. A communication method comprising: monitoring at a base station
a state of a reverse common channel; determining state information
of the reverse common channel corresponding to a result of
monitoring one slot allocated to the reverse common channel;
transmitting the state information combined with power control
information in a same slot to respective mobile stations through
the forward common channel; and randomly accessing slots to
transmit data to the base station on the reverse common channel
based on the state information combined with the power control
information.
18. A method as claimed in claim 17, wherein the state information
comprises: idle-normal state information representing a state in
which the reverse common channel is in an idle state and not
reserved by a particular mobile station, idle-reservation state
information representing a state in which the reverse common
channel is in a idle state and reserved by a particular mobile
station, busy-down state information representing both a state in
which the reverse common channel is in a busy state and a command
for reducing a transmission power to the mobile station, and
busy-up state information representing both a state in which the
reverse common channel is in a busy state and a command for
boosting a transmission power to the mobile station.
19. A method for performing a random access in a mobile
communication system, comprising: monitoring at a base station a
state of a reverse common channel; determining state information of
the reverse common channel corresponding to a result of monitoring
one slot allocated to the reverse common channel; and transmitting
the state information and power control information to respective
mobile stations through the forward common channel, wherein after
the transmitting step, the method further comprises: receiving and
analyzing at a respective mobile station state information of the
reverse common channel; and performing at the respective mobile
station a random access according to the state information, and
wherein the message transmission is stopped if two idle state slots
are detected by the mobile station in succession as a result of
monitoring the next slot after transmission of a message through an
arbitrary slot for performing random access.
20. A method of transmitting a frame of a forward common channel
from a base station to mobile terminal controlled by the base
station, comprising: dividing the frame into a plurality of random
access slots, each slot including information to be used by mobile
terminals when communicating with a base station on a reverse
common channel, wherein the information included in each slot
includes status information about whether the reverse common
channel is busy or idle combined with power control information
which is determined according to the status information, and
wherein a respective mobile terminal randomly accesses slots to
transmit data to the base station on the reverse common channel
based on the state information combined with the power control
information.
21. A method as claimed in claim 20, wherein a period of the frame
is 20 ms, the plurality of random access slots is equal to four
access slots, and each of the four access slots has a period of 5
ms.
22. A method as claimed in claim 21, wherein the status information
is represented by 3 bits, and the power control information is
represented by 1 bit.
23. A method as claimed in claim 20, wherein the status information
comprises: idle-normal state information representing a state in
which the reverse common channel is in an idle state and not
reserved by a particular mobile station, idle-reservation state
information representing a state in which the reverse common
channel is in a idle state and reserved by a particular mobile
station, busy-down state information representing both a state in
which the reverse common channel is in a busy state and a command
for reducing a transmission power to the mobile station, and
busy-up state information representing both a state in which the
reverse common channel is in a busy state and a command for
boosting a transmission power to the mobile station.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for performing a random
access in a mobile communication system, and more particularly, to
an improved method for performing a random access in a mobile
communication system.
2. Background of the Related Art
In general, a CDMA mobile communication system is provided with a
plurality of base stations BS each for providing radio
communication paths with a plurality of mobile station, a plurality
of base station controller BSC each for controlling operation of
the base stations, a plurality of mobile switching center MSC each
for switching call signals from mobile stations, and a home
location registration/visitor location registration HLR/VLR for
administrating mobility of mobile stations. A general origination
call processing procedure, which comes from each mobile stations in
a mobile communication system, will be explained with reference to
FIG. 1.
Referring to FIG. 1, upon a mobile station is provided with the
power, the base station transmits information for a pilot channel,
a synchronizing channel, and a broadcasting(call) channel to the
mobile station by turns(a1, b1 and c1). When the mobile station
issues the origination call, the mobile station requests the base
station for a call connection through the access channel(d1). In
this instance, the base station allocates a channel according to
request of the mobile station within its own cell or sector, for
allowing the call connection if the present reverse channel
communication capacity is below a preset threshold value, and if
the present reverse channel communication capacity exceeds a preset
threshold value, the base station allocates no channel for not
allowing the call connection(e1). As shown in FIG. 1, procedure
thereafter is a generally known procedure of transmission of a
preamble between the base station and the mobile station(g1), and
transmission of data between the base station and the mobile
station(h1). A random access method called as a slotted ALOHA has
been used in the IS-95B cellular CDMA mobile communication system.
In the Slotted ALOHA random access method, a plurality of slots
each having a predetermined slot period (i.g., 200 ms) are
allocated over a reverse common channel, and the mobile station
which will transmit the origination call starts to transmit a
message at a starting point of the slot for performing random
access.
FIG. 2 illustrates a timing diagram for explaining a random access
method(Slotted ALOHA) in the IS-95B cellular CDMA mobile
communication system, where `x` denotes a time point at which a
message to be transmitted is generated, and an arrow `1` denotes a
time point an actual transmission is performed irrespective of a
channel situation. A slot interval is defined to be longer than a
maximum length of a message. However, all access channel message
are transmitted during one slot. In such as random access method, a
size of an access channel slot is denoted as 4+PAM_SZ+MAX_CAP_SZ,
and values of the PAM_SZ and the MAX_CAP_SZ are determined by a
message broadcasted from the base station. In data transmission,
the mobile station always transmits an 1+PAM_SZ preamble, which has
a fixed size, before transmission of a 3+MAX_CAP_SZ message. For
example, if one frame is a 20 msec, the PAM_SZ value is 2, and,
when the MAX_CAP_SZ has a value 1, an size of an entire access
channel slots may be 140 msec. In the aforementioned related art
random access method, the base station can receive data transmitted
from one mobile station through a slot. If two mobile stations
compete for the same slot over a reverse common channel, the base
station receives only one signal of the two. If more than two
mobile stations compete for the same slot over the reverse common
channel, the base station may receive one of the signals. In the
random access method shown in FIG. 2, if a transmission message is
generated at a position X1 forward of a slot starting time point,
the transmission message can be transmitted at a starting point of
the slot without waiting time. However, if the transmission message
is generated at a position `X2` passed through the starting point
of the slot, transmission of the message may be waited until the
starting point `X3` of the next slot. If another transmission
message is generated during waiting for the starting point `X3` of
the next slot, there will be a contention problem in which the two
kind of messages collide to each other. Such an access method is
applicable to the IS-95B cellular CDMA mobile communication system
which has not so many mobile stations and a simple system without
any significant problem.
However, the aforementioned related art random access method may
not be applied to a mobile communication system developed after the
IS-95C which is based on multimedia information such as audio,
video, image, text and the like, because it is expected that mobile
communication system developed after the IS-95C has much more
subscribers registered therein compared to the mobile communication
system based on the IS-95B. Data will be multimedia information
such as audio, video, image and text having a variable length
depending on data characteristics. Therefore, if the random access
is performed in this environment according to the related art
random access, collision of the transmission messages is
vulnerable.
And, when the mobile station is performing random access using the
fixed sizes 3+MAX_CAP_SZ of slots, the transmission efficiency may
be lower. That is, because even one message which has a message
amount smaller than one slot size(for example, 80 msec or 40 msec)
occupies one slot completely, an unused portion of the slot is
wasted. Those disadvantages provides a cause to a lower a
transmission efficiency and, thereby deteriorating quality of
service in communication when many mobile stations perform random
access during a almost similar time.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to an improved
method for performing a random access in a mobile communication
system that substantially obviates one or more of the problems due
to limitations and disadvantages of the related art.
An object of the present invention is to provide an improved method
for performing a random access in a mobile communication system
which can improve a message transmission efficiency and minimize
random access failures.
Other object of the present invention is to provide a random access
slot architecture which can improve a transmission efficiency or
minimize a ratio of failure when a base station transmits
information on a reverse common channel state to respective mobile
stations.
Additional features and advantages of the invention will be set
forth in the description which follows, and in part will be
apparent from the description, or may be learned by practice of the
invention. The objectives and other advantages of the invention
will be realized and attained by the structure particularly pointed
out in the written description and claims hereof as well as the
appended drawings.
To achieve these and other advantages and in accordance with the
purpose of the present invention, as embodied and broadly
described, the method for performing a random access in a mobile
communication system, includes the steps of monitoring at base
station a state of a reverse common channel, determining state
information of the reverse common channel corresponding to a result
of the monitoring using one slot allocated to a forward common
channel, and transmitting the state information to respective
mobile stations through the forward common channel.
The method for performing a random access in a mobile communication
system of the present invention can improve a message transmission
efficiency because one random access slot allocated to the forward
common channel is used, not entirely, but partly(for a quarter), or
the state information of the reverse common channel is transmitted
repeatedly for a given times in a case when the base station
transmits state information of the reverse common channel to all
mobile stations within cells of sectors of its own. And, because
the mobile station performs a random access using a slot allocated
to the reverse common channel according to state information of the
reverse common channel transmitted from the base station, i.e., the
random access is performed according to the state information of
the reverse common channel broadcasted from the base station, a
possibility of data collision is reduced compared to the related
art. Accordingly, if the method for performing a random access in a
mobile communication system is applied to a mobile communication
system after the IS-95C which is based on multimedia information,
more improved random access method can be provide, providing an
improved communication quality.
It is to be understood that both the foregoing general description
and the following detailed description are exemplary and
explanatory and are intended to provide further explanation of the
invention as claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are included to provide a further
understanding of the invention and are incorporated in and
constitute a part of this specification, illustrate embodiments of
the invention and together with the description serve to explain
the principles of the invention:
In the drawings:
FIG. 1 illustrates a call connection procedure in IS-95A or IS-95B
cellular CDMA mobile communication system;
FIG. 2 illustrates a timing diagram for explaining a random access
method(Slotted ALOHA) in the IS-95B cellular CDMA mobile
communication system;
FIG. 3 illustrates a formation of a random access slot allocated to
a forward common channel in accordance with a preferred embodiment
of the present invention;
FIG. 4 shows an operation for transmission reverse common channel
state information from a base station to respective mobile stations
in accordance with a preferred embodiment of the present
invention;
FIG. 5 shows an occurrence of round trip delay allocated to a
forward common channel and a reverse common channel;
FIG. 6 illustrates states of a forward common channel and a reverse
common channel in accordance with a preferred embodiment of the
present invention; and,
FIG. 7 illustrates a flow chart for explaining an operation of a
mobile station in accordance with a preferred embodiment of the
present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Reference will now be performed in detail to the preferred
embodiments of the present invention, examples of which are
illustrated in the accompanying drawings.
In order to implement a random access method of the present
invention, the following new functions should be defined between
respective mobile station and respective base station.
First, the base station should monitor a reverse common channel
state periodically and provides state information of reverse common
channel to respective mobile stations through a forward common
channel, periodically.
Referring to FIG. 3, in a method for performing a random access in
a mobile communication system in accordance with a preferred
embodiment of the present invention, it is assumed that one frame
period of a forward common channel is 20 ms, and each frame
includes four RAS(random access slot) RAS0.about.RAS3 allocated
thereto. And, each of the random access slots RAS0.about.RAS3 has a
period of 5 ms, consisting of three channel information bits each
with a size of 1.25 ms CIB0.about.CIB2 and one power/reserve
control bit PCB. Transmission of the channel information bits
CIB0.about.CIB2 and the power/reserve control bit PCB may be varied
with situation and intention. For example, if only one message
which requires a random access is generated in a right prior slot,
transmission bits are formed as shown in FIG. 3 for improving a
reliability of the random access. Conversely, if at least two
messages each of which requires a random access are generated in a
right prior slot, the entire transmission bits may be formed of
channel information bits. The base station may set the value of
channel information bits CIB0.about.CIB2 and the power/reserve
control bit PCB allocated to one frame to A0"-idle status: I, or
A1"-busy status B, respectively.
Though each of the channel information bits CIB0.about.CIB2 may be
represented with only one bit, in one embodiment of the present
invention, each of the channel information bits CIB0.about.CIB2 has
a (3,1) block code type which transmits three channel information
bits repeatedly, taking a high probability of bit error occurrence
in a radio environment and a consequential random access
performance deterioration into consideration. TABLE 1 below
illustrates an embodiment in which the channel information bits
CIB0.about.CIB2 and the power/reserve control bit PCB of each slot
transmitted from a base station to a forward common channel are set
to "0"-idle status: I, or "1"-busy status: B.
TABLE 1 Transmission bits denotes 0000 Idle - Normal : IN 0000 Idle
- Reservation : IR 1110 Busy - Down : BD 1111 Busy - Up : BU
In table 1, the idle state with `0` value denotes a state in which
a power intensity of each signal received from the base station
through the reverse common channel does not exceeds a threshold
value, or a state in which the signal is not decodable because
synchronization is not matched. While the busy state with `1` value
denotes a state in which total power of signals received at the
base station through the reverse common channel exceeds a threshold
value, i.e., a state in which there is no empty channel, presently.
Referring to table 1, transmission bits transmitted from the base
station to respective mobile stations are any one of Idle-Normal:
IN, Idle-Reservation: IR, Busy-Down:BD, and Busy-Up: BU. The
Idle-Normal: IN denotes a state in which the reverse common channel
is idle and reserved by no mobile station, allowing all mobile
station to perform random access thereto. The Idle-Reservation: IR
denotes the reverse common channel is idle and reserved by a
specific mobile station, allowing only the specific mobile station
for the random access. The Busy-Down: BD denotes the reverse common
channel is busy and a command to the mobile station to decrease a
transmission power, and the Busy-Up: BU denotes the reverse common
channel is busy and a command to the mobile station to increase the
transmission power.
Second, as shown in FIG. 3, the base station should determine the
power control command before the starting points of state
information on the reverse common channel and each of the random
access slot RAS0.about.RAS3 allocated to the reverse common
channel. In the method for performing a random access in a mobile
communication system, sizes of slots allocated to the forward
common channel is the same with the reverse common channel. In this
instance, as shown in FIG. 5, the slots respectively allocated from
the base station to the forward common channel and the reverse
common channel are involved in a time delay as much as a round trip
delay, since frames used in the forward common channel and the
reverse common channel are not synchronized each other.
Accordingly, in the method for performing a random access in a
mobile communication system of the present invention, the base
station synchronizes the slots received from respective mobile
stations to the slots of the forward common channel before use.
Third, the state information over the reverse common channel
transmitted from the base station to respective mobile stations
should be fed back continuously using a portion of broadcasting
channel. That is, as shown in FIG. 4, if the state information on
the reverse common channel transmitted from the base station BS1 to
respective mobile stations in its own cell or sector is the idle
status bit I, the mobile station MS1 can perform a random access
through a random access slot allocated to the reverse common
channel. In FIG. 4, it is shown that the reverse channel is kept
busy while the mobile station MS1 transmits data. In such a case,
other mobile stations perform no random access until there is a
random access slot in a idle state. However, if the call from the
mobile station MS1 is released, for the base station to transmit
state information on the reverse common channel containing the idle
status bit `I`, another mobile station MS2 can perform a random
access through a random access slot allocated to the reverse common
channel.
Functions of the mobile station to be defined newly are as
follows.
First, as shown in FIG. 6, each mobile station should monitor a
random access slot allocated to the forward common channel,
periodically. That is, each mobile station should monitor both
channel information bits CIB0.about.CIB2 contained in each random
access slot allocated to the forward common channel and control
bits PCB contained as necessary before performing a random access
at a starting point of every random access slot RAS0.about.RAS3.
When the mobile station performs random access, the mobile station
provides a message for performing the random access from a starting
point of an odd numbered random access slot RAS1 or RAS3 if the
reverse common channel represented by channel information bits in a
prior random access slot RAS0 is in a idle state. In this instance,
bits received from the base station includes three channel
information bits CIB0.about.CIB2 and one power/reservation control
bit PCB as shown in TABLE 2, below.
TABLE 2 Received bits Denotes 0000, 0010, 0100, 1000 Idle - Normal
: IN 0001, 0011, 0101, 1001 Idle - Reservation : IR 1110, 1100,
1010, 0110 Busy - Down : BD 1111, 1101, 1011, 0111 Busy - Up :
BU
As shown in TABLE 2, the bits each mobile station is received from
the base station will be any one of Idle-Normal: IN,
Idle-Reservation IR, Busy-Down: BD, and Busy-Up: BU. There are four
kinds of received bits in each row in TABLE 2 for showing cases
when bit transmission errors are occurred in a process that the
bits are transmitted from the base station to the mobile station.
Although the three channel information bits used in the present
invention, at lease one channel information bits are considered to
be bits having actual data transmitted from the base station. The
received bit used herein has the same meaning explained in the case
of the transmission bit.
Second, if two random access slots in idle states are detected in
succession after the mobile station transmits the message as a
result of monitoring the next random access slots, the transmission
should be stopped as it is considered that the random access is
failed.
FIG. 7 illustrates a flow chart for explaining an operation of a
mobile station in accordance with a preferred embodiment of the
present invention, referring to which a method for performing a
random access in a mobile communication system will be
explained.
The base station monitors a state of the reverse common channel,
periodically(S1). Then, the base station determines a transmission
type of transmission bit corresponding to the state of the reverse
common channel for every random access slot allocated to the
forward common channel(S2). That is, as shown in TABLE 1, it is
determined whether the transmission bit transmission type is a
(3,1) block code type which includes 3 channel information bits and
one control bit which uses a random access slot, or another
transmission type. Then, the base station transmits the prepared
transmission bits to all mobile stations within cells or sectors of
its own using the forward common channel(S3). In this instance,
when the transmission bit transmission type is the (3, 1) block
code type, the transmission bits for informing the reverse common
channel state will be one of IN, IR, BD and BU shown in TABLE 1. In
the present invention, it is desired that if the transmission bits
from the base station to the mobile station are IRs, the base
station transmits the IRs in succession loaded on two slots for
preventing occurrence of transmission error. The mobile station
monitors the transmission bits(received bits in view of the mobile
station) broadcasted from the base station, periodically(S4). Then,
the mobile station performs a random access according to the state
information of the reverse common channel contained in the received
bits(S5). In this instance, if a first random access slot is
defined as RAS0, the mobile station transmits a message for
performing a random access in the base station when the odd
numbered random access slots RAS1 and RAS3 are at IN. In contrast,
the mobile station having confirmation of reservation from the base
station transmits the message for performing a random access only
in a case when the present reverse common channel state is IR.
While each mobile station transmits the data and receives the state
through the forward common channel, it is possible that a mobile
station start transmission within a RAS, and then another mobile
station may try transmission within another RAS since a time delay
of 2 RAS for respective mobile stations in transmission is
occurred.
In the meantime, a mobile station which is performing random access
adjusts transmission power according to a value of a power control
bit PCB transmitted through the forward common channel. That is,
the mobile station increases the transmission power if the received
bit is BU, and decreases the transmission power if the received bit
is BD.
If two random access slots RASs in idle states occur in succession
during performing random access, the transmission of message is
stopped, taking a possibility of state bit transmission error
occurrence for the two random access slots RASs or the random
access slot RAS in an idle state occurred for the first time after
the mobile station starts to perform the random access into
account. The transmission power is not changed for the random
access slot RAS in an idle state occurred when the mobile station
is performing random access.
The mobile station, having the random access finished, determines a
reverse common channel state of the next random access slot for
verifying a proper random access. If the reverse common channel
state of the random access slot RAS is busy after finish of the
random access, it is determined that the random access is performed
properly, and if the reverse common channel state of the random
access slot RAS is idle, it is determined that the random access is
failed, and the random access is performed, again.
As has been explained, the method for performing a random access in
a mobile communication system of the present invention can improve
a message transmission efficiency because one random access slot
allocated to the forward common channel is used, not entirely, but
partly, or the state information of the reverse common channel is
transmitted repeatedly for a given times in a case when the base
station transmits state information of the reverse common channel
to all mobile stations within cells of sectors of its own. And,
because the mobile station performs a random access using a slot
allocated to the reverse common channel according to state
information of the reverse common channel transmitted from the base
station, i.e., the random access is performed according to the
state information of the reverse common channel broadcasted from
the base station, a possibility of data collision is reduced
compared to the related art. Accordingly, if the method for
performing a random access in a mobile communication system is
applied to a mobile communication system after the IS-95C which is
based on multimedia information, more improved random access method
can be provide, providing an improved communication quality.
It will be apparent to those skilled in the art that various
modifications and variations can be performed in the method for
performing a random access in a mobile communication system of the
present invention without departing from the spirit or scope of the
invention. Thus, it is intended that the present invention cover
the modifications and variations of this invention provided they
come within the scope of the appended claims and their
equivalents.
* * * * *